Thermoinsulating knapsack

ABSTRACT

The present invention relates to a thermoinsulating knapsack for carrying beverages, comprising a sack ( 1 ) provided with straps ( 2 ) for transportation on the back, inside which is arranged a container ( 3 ) for a beverage. Said container ( 3 ) is provided with an opening into which is inserted a flexible tube ( 4 ) which enables the beverage to be sorbed. One or more evacuated panels ( 5, 6 ) comprising an envelope which encloses powder of an inert material with average particle size lower than 100 nanometers are arranged between said sack ( 1 ) and said container ( 3 ).

[0001] The present invention relates to a knapsack for sportsmen,suitable for carrying water or other beverages while maintainingconstant their temperature and for drinking said beverages withouthaving to take the knapsack off

[0002] It is known that the people who train a sport activity for a longperiod of time need to drink frequently in order to avoid becomingdehydrated. Since some kinds of activities, such as cycling, keepconstantly busy the hands of the sportsman, a knapsack has been devisedwhich internally comprises a container for a beverage. Said container isprovided with a thin tube through which the beverage can be sorbed bythe sportsman, so that he can drink without having to stop his activity.The knapsack can be thermally insulated by means of fibrous insulators,such as glass wool or rock wool.

[0003] However, the insulating features of these materials are notsufficient for maintaining constant the temperature of the beverage fora long period of time.

[0004] In order to obviate this problem, it was thought to manufacturethe thermal insulation of the knapsack by using thermoinsulatingevacuated panels of the known type, for example those formed of a boardof open-cells polymeric foam contained in an evacuated envelope.

[0005] However, these panels are rigid and can be with difficultyadjusted to the walls of the knapsack that preferably has an anatomicaland optionally non-rigid shape, with a higher volume when it is filledof the beverage and a progressively decreasing volume when the beverageis consumed.

[0006] Further, since a substantial requirement of said envelope is ahigh gas-tightness, it is formed of barrier sheets containing aluminumlayers which confer to the envelope itself a certain fragility.Therefore, said panels should be placed inside a preferably rigidprotective structure in order to avoid the cracking of the envelopeswhich would compromise the thermal insulation properties of the panels.

[0007] Therefore, object of the present invention is providing athermoinsulating knapsack which is free from the above mentioneddrawbacks. Said object is achieved by means of a thermoinsulatingknapsack whose main features are specified in the first claim and otherfeatures are specified in the following claims.

[0008] The panels used for the thermal insulation of the knapsackaccording to the present invention employ, as a filling material, apowder of an inert material having average particle size lower than 100nanometers (nm) and preferably comprised between about 2 and 20nanometers, It has been found that by the use of these powders, thethermal conductance of the panels varies only slightly, and particularlyremains lower than about 8 mW/m·K, for internal pressures up to a fewtens of unbar, differently from the panels based on polymeric foamswherein the thermal conductance grows rapidly when the internal pressureis higher than about 1 mbar. For this reason, it is possible to maintainpressures even higher than 10 mbar inside the evacuated panels accordingto the invention, so that it is not necessary to use envelopes whichcontain aluminum sheets, necessary above all in the applications at hightemperature. This particular measure, which reduces at negligible valuesthe thermal bridge, enables the nearly total utilization of theinsulating properties of the filling material of the evacuated panelsaccording to the invention. Due to their very reduced size, theparticles of the powders can form, because of cohesive or electrostaticforces, aggregates having size of a few micrometers (μm) or even higher,without causing variations of the thermal insulation properties of thepanels.

[0009] By using as a filling a block of very fine powder of an inertmaterial, it is possible to obtain evacuated panels which can be bent orcurved, so that they can be adapted to the anatomical shape of theknapsack inside which they have to be inserted, as well as to theeventual variations of shape and volume of the container when it isfilled or emptied of the beverage.

[0010] Further, thanks to their envelope being formed of a plasticmultilayer comprising no aluminum layers, the evacuated panels used forthe thermoinsulating knapsack according to the present invention aremore solid than the known panels based on polymeric foams and can beplaced inside the same knapsack without providing a protective structuresuitable for preventing the accidental cracking of the envelopes.

[0011] According to a particular aspect of the invention, the inertmaterial of the powder is silica preferably mixed with numeral fibers,so that it can be easily compressed in order to make blocks of even afew millimeter thickness, which can be placed in an envelope, evacuatedand subsequently curved with relative ease.

[0012] Further advantages and features of the knapsack according to thepresent invention will appear to those which are skilled in the art fromthe following detailed description of one embodiment thereof withreference to the accompanying drawings, wherein:

[0013]FIG. 1 shows a perspective view of the complete thermoinsulatingknapsack according to said embodiment; and

[0014]FIG. 2 shows a perspective view of the knapsack of FIG. 1 fromwhich the external sack has been removed.

[0015] With reference to FIG. 1, there is shown that the knapsackaccording to said embodiment of the present invention comprises a sack 1made of a flexible material, for example fabric, provided with twostraps 2 for transportation on the back. Inside said sack 1 ispositioned a container 3 made of a liquid-tight material, suitable forcontaining water or another refreshing beverage Said container iscompletely closed with the exception of a small upper opening suitablefor enabling the coining out of the drink by means of a small tube 4having the function of a straw. As a matter of fact, one end of saidtube 4 is immersed into the beverage inside the container, whereas theother end is inserted between the lips of the sportsman when he wishesto drink.

[0016] In the present embodiment the container 3 is formed of anenvelope made of a flexible material, for instance plastic sheets, butthe use of any other material known for containing alimentary beveragescan be involved in other embodiments.

[0017] Tube 4 can be fastened at the central portion thereof to one ofthe straps 2 so that it is always within the reach of the sportsman.

[0018] With reference to FIG. 2, two evacuated, slightly curved panels 5and 6 are shown to be positioned externally of container 3. Said panelsare arranged side by side so that together they form a substantiallytubular body whose cavity is occupied by container 3. Besides, the twoevacuated panels 5 and 6 can be fastened to one another by gluing orwelding in pairs their lateral flanges.

[0019] Evacuated panels 5 and 6 have a thickness comprised for examplebetween 4 and 15 mm and are formed of an envelope of a laminatedplastic, optionally metallized, wherein a very fine powder of an inertmaterial is enclosed, particularly silica. The plastic material used forthe envelope can be any known material which is considered to besuitable for the construction of evacuated panels of traditional type,for example a polyolefin. The pressure inside the envelope is lower than50 mbar, whereas the silica powder is preferably mixed to with mineralfibers, particularly glass fiber. The silica is preferably pyrogenicsilica, a form of silica which is obtained by burning SiCl₄ with oxygenin a suitable chamber, according to the reaction:

SiCl₄+O₂→SiO₂+2 Cl₂

[0020] The silica produced in this reaction is in the form of particlesof size comprised between a few nanometers and a few tens of nanometers,which can optionally be agglomerated to form particles of bigger size,as previously described. Pyrogenic silica is produced and sold forinstance by the US company CABOT Corp. under the name Nanogel® or by theGerman company Wacker GmbH.

[0021] In the present embodiment the internal space of the sack 1 iscompletely occupied by container 3 and by insulating panels 5 and 6placed around it, but in other embodiments said sack 1 could be providedwith more compartments and lateral pockets so as to serve for thetransportation of other objects or food, further to the beverage.

[0022] Further variations and/or additions can be made by those whichare skilled in the art to the described and illustrated embodiment byremaining within the limits of the invention itself.

1. Thermoinsulating knapsack for carrying beverages, comprising a sack(1) provided with straps (2) for transportation on the back inside whichis arranged a container (3) for a beverage provided with an opening intowhich is inserted a flexible tube (4) which enables the beverage to besorbed, characterized in that one or more evacuated panels (5, 6)comprising an envelope which encloses powder of an inert material withaverage particle size lower than 100 nanometers are arranged betweensaid sack (1) and said container (3).
 2. Thermoinsulating knapsackaccording to the preceding claim, characterized in that the particles ofthe powder of inert material have an average size comprised between 2and 20 nanometers.
 3. Thermoinsulating knapsack according to one of thepreceding claims, characterized in that the envelope is made of aplastic, optionally metallized material.
 4. Thermoinsulating knapsackaccording to one of the preceding claims, characterized in that thepowder of inert material is mixed with mineral fibers. 5.Thermoinsulating knapsack according to the preceding claim,characterized in that said mineral fibers are glass fibers. 6.Thermoinsulating knapsack according to one of the preceding claims,characterized in that said inert material is silica.
 7. Thermoinsulatingknapsack according to the preceding claim, characterized in that thesilica is pyrogenic silica.
 8. Thermoinsulating knapsack according tothe preceding claim, characterized in that said evacuated panels (5, 6)have a thickness comprised between 4 and 15 mm.
 9. Thermoinsulatingknapsack according to one of the preceding claims, characterized in thatsaid evacuated panels (5, 6) are two and that they are curved andmutually fastened by means of their flanges so that together they form atubular body whose cavity is occupied by the container (3).